Under-cutting tool



1951 F. SCHE'RMERHORN 2,537,709

UNDER-CUTTING TOOL Filed March 21, 1947 Z/ Free 712 an Shermeriwrn I I 3" QMQW4W Atfo rney:

I atented Jan. 9, 1951 a UNDER-CUTTING TOOL Freeman Schermerhorn, Pierz, Minn., assignor of one-half to William Holroyd, Foley, Minn.

Application March 21, 1947, Serial No. 736,326 1 Claim. (o1. 29-96) This invention relates to improvements in lathe tools, and more particularly to an improved undercutting attachment for lathes, especially although not necessarily for undercutting laminations and the like of a cylindrical member, such as the mica laminati'ons of an electric motor commutator.

A primary object of this invention is to provide a simple and efficient tool of the character indicated whose cutting element is readily replaceable.

Another important object of this invention is to provide a tool of the character indicated which is composed of a minimum number of simple and rugged parts which are easily made and assembled at low cost, and which can be madefrom scrap material so as to further reduce the cost.

Other important objects and advantageous features of this invention will be apparent from the following description and the drawings appended thereto, wherein merely for purposes of illustration, a preferred embodiment is set forth in detail.

In the drawings:

Figure 1 is a top plan View thereof;

Figure 2 is a bottom plan view;

Figure 3 is a left hand side elevation;

Figure 4 is a right hand side elevation;

Figure 5 is a transverse section taken through 5-5, Figure 1, on a somewhat enlarged scale;

Figure 6 is a fragmentary longitudinal sectional view on an enlarged scale, taken on the line 6-4; of Figure 3, and

Figure 7 is a side elevation, on a somewhat enlarged scale, of the blade retaining plate, partly broken away to show structural details.

Referring in detail to the drawing, the herein illustrated tool comprises a shank 8, for mounting on a lathe tool-post (not shown), of relatively narrow, flat, parallel sided form terminating at its heel in a downwardly angulated surface 9 and flared at its opposite end, as indicated at Ill, into a generally rectangular head ll.

As shown in Figures 3 and 4, the upper surfaces of the shank 8 and flared portion H] are forwardly and downwardly curved, as indicated at 12, and the lower surfaces thereof are forwardly and upwardly curved, as indicated at 13, with the result right hand side of the head n is formed with a vertical slot H to accommodate a portion of the retainer plate. A vertical screw threaded hole 18 is formed through the head I midway between the sides of the head and an appropriate distance behind the front edge of the slot [5, to accommodate a clamping stud IS.

The blade 20, which may appropriately be a. length of discarded hacksaw blade, with the slanting sides of the teeth 2| toward the right hand side of the head ll, seats in the blade slot IS with its toothed edge extending beyond the terminal IA of the head, and is held in place by the blade retainer plate 22.

The retainer plate 22 comprises a flat rectangular horizontal plate portion 23, fitting the dimensions of the slot l5 and having a downturned forward edge 24 shaped to conformably engage the upper surface of the blade 20, and a plate-like vertical side 25 to engage in the slot I! of the head I l.

The horizontal plate portion 23 is formed with a smooth hole 26 freely but closely passing the threaded shank of the clampingstud l9, this hole being so positioned that when the stud is passed therethrough and threaded into threaded hole l8 of the head i I, the blade retainer plate portion 23 will conform to the head slot l5 and its vertical flange 25 will conformably engage the side slotl'l. With the blade20 in place in the slot 16, further tightening of the stud I9 operates to forcibly engage the downturned edge 24 with the blade 20 so as to securely retain the same in place with its back edge against the back of the blade slot I6 and its right hand end against the flange 25. In this way the blade 20 cannot shift or get out of alignment in the tool in ordinary use, but can be quickly and easily removed and replaced by loosening and retightening the stud l9.

Various modifications and changes are contemplated and may obviously be resorted to without departing from the spirit and scope of the invention as claimed hereinafter. Having described the claimed as new is:

An under-cutting tool for mounting in a tool post of a lathe, comprising an elongated shank having a forward end provided with a widened head, said head having a top surface provided with a stepped portion including an outer lower step and an inner upper step, said lower step opening outwardly of the forward end of the head and each of the steps extending from side to side of the head, said head having a threaded bore opening upwardly into the inner upper step, a blade retaining plate conformably seating in said invention, what is inner upper step having a forward downturned edge extending toward the lower step, a transversely elongated blade conformably seated in said lower step beneath the downturned edge of the blade retainer plate having a transversely extending cutting edge spaced outwardly from the forward end of said head, said blade having a back edge abutting against a portion of the head disposed between the steps, said head having a threaded bore opening upwardly into the inner upper step, and a clamping stud extending downwardly through the blade retainer plate and threadedly engaging in said threaded. bore for clamping the plate against the upper step and for retaining the downturned forward edge. of the plate in clamping engagement with the blade for clamping said blade against the enter lower step, said blade retaining plate having a depending flange at one side edge thereof engaging a side edge of the head and one end of the blade for accurately positioning and retaining the blade against shifting movement transversely of the head, said cutting edge of the blade comprising a row of teeth all inclined in a direction away from the depending flange of the blade retainer plate.

R AN SCHERME H RN- REFERENCES CITED The following references are of record in the file of this patent:

FOREIGN PATENTS Number Country Date 130,717 Great Britain July 29, 1919 675,156 Germany May 5, 1931 

